Náttúrufræðingurinn - 1984, Side 45

Ingvi Þorsteinsson & Gunnar Ólafsson.
1967. Fjárbeit í skóglendi og úthaga . —
Ársrit Skógr. fél. ísl. 1967: 6—14.
Levy, E. B. & E. A. Madden. 1933. The
point method of pasture analysis. —
N. Z. J. Agric. 46: 267-279.
Mueller-Dombois, D. & H. Ellenberg.
1974. Aims and Methods of Vegetation
Ecology. — John Wiley & Sons, New
York.
Sigurður Þórarinsson. 1961. Uppblástur á
fslandi í ljósi öskulagarannsókna. —
Ársrit Skógr.fél. ísl. 1960—61: 17—51.
Steen, E. 1958. Betesinflytelser i svensk
vegetation. — Statens jordbruksförsök.
Meddelande nr. 89. Uppsala.
Steindór Steindórsson. 1966. Um hálendis-
gróður íslands, III. - Flóra 4: 49-94.
Svanhildur Jónsdóttir Svane. 1963. Um
mosaþembugróður. — Náttúrufræðing-
urinn 33: 233—263.
Whitman W. C. & E. I. Siggeirsson. 1954.
Comparison of line interception and
point contact methods in the analysis of
mixed grass range vegetation. — Eco-
logy 35: 431-436.
Wielgolaski, F. E. 1975. Comparison of
plant structure on grazed and ungrazed
tundra medows. - í: F. E. Wielgolaski
(ritstj.): Fennoscandian Tundra Eco-
systems. Part 1 Plants and Microorgan-
isms. 86—93. Springer, Berlin.
Wilson, J. W. 1960. Inclined point Qua-
drats. — New Phytol. 59: 1—8.
Winkworth, R. E. 1955. The use of point
quadrats for the analysis of heathland.
- Aust. J. Bot. 3: 68-81.
Þorleifur Einarsson. 1962. Vitnisburður
frjógreiningar um gróður, veðurfar og
landnám á íslandi. - Saga III: 442-
469.
SUMMARY
Effects of grazing on
the vegetation
on Auðkúluheiði heathland,
Northern Iceland
by
Ingibjörg Svala Jónsdóttir,
Department of Plant Ecology,
University of Lund,
Östra Vallgatan 14,
S-223 61 Lund,
Sweden.
The aim of this study was to elucidate
how long lasting sheep grazing has
changed the vegetation on Auðkúluheiði
heathland, North-Iceland. During the
summer of 1979 the vegetation cover was
measured on three transects over
topographical gradients on a small islet in
the Lómatjarnir lake (Fig. 1). For com-
parison, the vegetation cover in the sur-
rounding grazed area was measured on
similar transects. The lake covers an area
of 0.3 km2 and is situated 430 m above sea
level. The islet is a low ridge, 390 m long,
and reaches 9 m above the water level at
its highest point. Auðkúluheiði heathland
has been grazed during the summer for
centuries, but the islet has presumably
always been protected from grazing.
The method used for measuring the per-
centage cover of vegetation was the point-
quadrat method, discussed by Levy &
Madden (1933), Drew (1944), Goodall
(1952), Winkworth (1955), Mueller-Dom-
bois & Ellenberg (1974) and other. A
50x50 cm frame with 100 equally distri-
buted pin positions was used (Fig 2). Three
different vegetational layers were recog-
nized: moss layer, field layer and shrub
layer, and only one record was made in
each layer. In order to minimize the error
due to pin diameter, the contacts with the
sharpened point of the pin were recorded
instead of the contacts with the pin itself.
Litter was also recorded if found. One
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